During the Phase I project, the PI has prepared florescent glutathione probes for the study of glutathione (GSH) receptors in the CNS. One of these probes shows promise as a potential replacement for radiolabelled GSH for the study of these receptors. In the Phase II portion of the project, the PI plans to continue preparation of such fluorescent probes with an ultimate aim toward not only maximizing the binding parameters for the GSH receptor but also with the aim of identifying that portion of the molecule which contributes to the binding to the receptor. In addition, the probes prepared by the PI will be used for comparison with radiolabelled GSH as a probe for studying the GSH receptor in astrocytes and/or human spinal cord.